Preparation of metallic hydrocarbonyls



United States Patent O PREPARATION F METALLIC HYDRO CARBONYLS Joseph K.Mertzweller, Baton Ronge, La., assigner to Esso Research and EngineeringCompany, a corporation of Delaware VApplication September 7, v19511,Serial No. 245,599

Claims. (Cl. 23-50) This invention relates to a novel process for thepreparation of metallic hydrocarbonyls and their salts.

The metallic hydrocarbonyls (carbonyl hydrides) and their salts are ofpotential importance as catalysts for many synthesis processes. Anoutstanding example is the oxo or hydroformylation reaction in whichaldehydes and alcohols are obtained by treating olens with carbonmonoxide and hydrogen in the presence of a cobalt catalyst. While manyforms of cobalt may be utilized, it is considered by most investigatorsthat these are converted to cobalt hydrocarbonyl under synthesisconditions, and that this compound functions as the actualhydroformylation catalyst.

It is thus apparent that it would be advantageous to have a source ofthis compound.

While several preparations of cobalt hydrocarbonyl are described in theliterature, most of these are rather inconvenient and many require theisolation of cobalt carbonyl as an intermediate.

This invention provides a simple and novel process for preparation ofaqueous solutions of metallic hydrocarbonyls and their salts, andparticularly cobalt hydrocarbonyl H[Co(CO)4]. The process comprisestreating an aqueous solution of a cobalt salt of an organic or inorganicacid with carbon monoxide and hydrogen at elevated pressures andtemperatures. It is also necessary that the treatment be carried out inthe presence of a suitable organic solvent to obtain appreciable yieldsof cobalt hydrocarbonyl. Apparently the conversion of the cobalt salt tothe desired product takes place in the organic solvent and is thensimultaneously extracted by the aqueous phase. The latter uponseparation from the organic solvent gives the desired product in aqueoussolutions.

The cobalt salts that can be utilized in the process of this inventioncomprise organic and inorganic salts of cobalt, including such salts ascobalt acetate or cobalt formate. The salts are utilized preferably inaqueous concentrations in the range of about 2-5 Wt. percent cobalt.

The organic solvents utilized in the process of this invention have thefollowing characteristics: insolubility in water, and inertness underthe reaction conditions. In general the inert oxygenated solvents aremost desirable, but saturated or aromatic hydrocarbons can also beemployed. Solvent is generally in the range of -100% on aqueoussolution.

rIhe best solvents consist of inert oxygenated solvents, especially theprimary aliphatic alcohols or aldehydes having 4 or more carbon atomsper molecule. Crude mixtures of primary aliphatic aldehydes or alcoholssuch as are obtained by decobalting oxo products or by hydrogenation ofthe products of the hydroformylation reaction also function as ecientsolvents. lso-octyl aldehyde is an especially good solvent. As statedabove, the

l conversion of the cobalt salt starting material to the cobalt carbonylhydride takes place in the organic solvent ice and then the anion isselectively extracted by the aqueous phase, giving cobalt hydrocarbonylor its cobalt salt.

The reaction temperature is maintained in the range of to 180 C. with apressure of 1,000 to 4,000 p. s. i. g. Preferable contactV times rangefrom 1/2 Vto 6 hours. Synthesis gas is employed in considerablestoichiometric excess (generally 10-100 fold) with respect to cobalt.Hydrogen to carbon monoxide ratios are generall;l in the range of1/1,'although 0.5-4.0/ 1 may be used.

This invention will be better understood by reference to the ow diagramshown in the drawing.

In the system shown the aqueous cobalt salt solution enters reactor 1through line 2. Hydrogen and carbon monoxide enter reactor 1 throughlines 3 and 4. A countercurrent contacting is thereby effected. Intimatemixing is carried out in reaction zone 1. The aqueous layer Withdrawnfrom reaction zone 1 through line 5 contains cobalt hydrocarbonyl aswell as Unconverted cobalt salts and is sent through line 6 into highpressure separator 7. The organic solvent is withdrawn from reactionzone 1 through lines 8 and 6 to high pressure separator 7. Unconvertedcarbon monoxide and hydrogen are Withdrawn from high pressure separator7 maintained at approximately the same pressure and temperature range asreactor 1 through line 9. The combined liquid mixture of aqueous andorganic liquids is withdrawn through line 10 through cooling coil 11 andautomatic pressure reducer 12 to settler 13. In settler 13 the twophases are separated into an upper organic phase and a lower aqueousphase. The lower aqueous phase, comprising the aqueous solution ofcobalt hydrocarbonyl with Unconverted cobalt salts which do notinterfere with the `efllcacy of the former, is withdrawn through line14. The organic solvent is withdrawn through line 15 and can be recycledthrough line 4 to reactor 1.

The following examples further illustrate the details of this inventionand highlight its advantages.

Example I.Synthess in the absence of solvents Product Feed Hour 1 Hour 3Hour 5 Hour l2 Acidity, Wt. Percent as HAC 0.93 0. 98 l. 01 l. 03 1. 16Cobalt (as Coi-t) 3. 27 3. 27 3.18 3.19 3. 18 Cobalt (as hydrocarbonyl)nil trace trace trace The products from hour 3 on contained small tracesof cobalt hydrocarbonyl as evidenced by the formationV of small tracesof yellow precipitate (cobalt carbonyl) when the solutions were exposedto air. The concentrations of cobalt hydrocarbonyl were too srnall to beanalyzed directly, but it is estimated by the differences in Co++concentrations between the feed and products that not more than 3% ofthe cobalt was converted and this conversion was achieved at the end ofthree hours and did not increase when the treatment was continued for atotal of twelve hours. This example illustrates the necessity ofutilizing the indicated types of organic solvents in the process asshown inrExample II.

Example Il Y Synthesis in the presence of solvents is illustrated by thefollowing. All treatments were for six hours with hydrogen/CO ratioabout 1.1/1.

Feed Aqueous Cobaltous Acetate Aqueous Cobaltous Acetate Y Cobalt Conc.,Wt. Percent- 3.43.. 3.43.. 3.43.. 3.43.. 3.27-..- 3.V .27., 1 Free AcidAcetic Acetic Acetic Acetic Acetic Acetlc Acctic Acetic Y Conc., Wt.Percent 1.1.- 1.1.- 1'.l. 1.1.- l.1 l 1----- .93.

Solvent.'.....-.. Iso-0ctyl Iso-Octyl Iso-Octyl Iso-Octyl Iso-0ctylIso-Octyl Hydro, Fract. Y Aldehyde. Aldehyde. Aldehyde. Aldehyde.Alcohol Alcohol Product Btms. Solvent/Water, Vol. Ratio lll... 1/1.. 11/1- 1/1.- /1 1/1. Temperature, 9 C--. 79 107 Y 149 177 107 177 7 107.Pressure, p. sz'i. g. (At Start) 3,150 3,000.A 2,900.... 3,200.-.--2,900 3,000 2,925. 2,900 Cobalt Distribution, Wt. Percent of Y CobaltCharged:Y Y

In Solvent' 1 6 2Q 41 32 48 45 1, .In Water as Co-H' 102 45 11 25 15 1616 99. In Wateras [00(0 O)4]ion. nil- 44 39 2s 21 19 28 Trace Crilalt,Accounted For, Wt. Percent o 102 95 99 94 RR 8? 89 K 99.

arge.A Y Concentration of Hydrocarbonyl Vanion 4.33.. 4.03.- 2.97..2.28-. 2.l4.- 2.70

nVater, Wt. Percent.

It is indicated by these dataV that the choice of solvent is important.For example, iso-octyl aldehyde gives the maximum concentration ofcobalt hydrocarbonyl at 107 C., whileiSo-octylralcohol (iinishedproduct) gives less hydrocarbonyl at 107 C. and proportionately morecobalt in the solvent. The crude hydro product was intermediate whilefractionator bottoms (bottoms from disf tillation of Vhydro 'productcontaining unsaturated 0rganic compoundslwas very ineffective,V givingresults about equivalent to those obtained in the absence of solvents.

The obtaining of the cobalt Vhydrocarbonyl cobalt salt in aqueoussolutions is a distinct advantage, as it isstable' 'in water atatmospheric temperatures and pressures and also elevated temperaturesand pressures. This type of product is obtained by allowing theconversion tov proceed to such an extent that there remains intheaqueous phase a stoichiometric equivalent or an excess of the Co++ ionwith respect to the Co(CO)4 ion. Vlf necessary this relationship may beachieved by adding a source of Co++ to the reaction product. The uniquestability of the cobalt salt is illustrated by the following example:

Example III Y An aqueous solution similar to the above describedsolution showed the following composition:

Sp. gr. (78 F.) 1.0736 Total acid (wt. percent) as acetic acid 0.79Cobalt, Wt. percent as Coi+ 2.39 Y Cobalt, VWt. percent as Co(CO)4 n1.52

315 cc. of this solution was concentrated byk distilling off water atatmospheric pressure until the residue amounted to 218 cc. Thisrepresents a volume decrease of 30.8%. The'residuewas analyzed and hadthe following composition:

Sp. gr. (78 F.) 1.108 Total acid (Wt. percent `as HAC) 0.64 Cobalt, wt.percent as Co++ Y 3.12 Cobalt, wt. percent as Co(CO)4 2.00

These data show that the cobalt constituents increased in concentrationVinrproporti'on to the decrease in volume 'potV the solution, therebeing .little or no loss in hydron carbonyl anion.

V1f desired, pure Vcobaltcarbonyl canbe obtained by i Vtreating theaqueous solutions with air under acidic conditions. Y Y

Another method of conducting the'process of this in- Vvention is bytreating the cobalt salt with the indicated gaseous mixture in anorganic solvent exclusively, giving largely the cobaltcarbonyl hydrideHCo(CO)4 Exprior to contacting said solution vwith organic Vlt is to beunderstood that the invention isnotlimited Y to the specific examples,which have'been oiered merely as illustrations, and thatmodifications'maybe madeV inVV equipment and conditions Within the rangespecified Without departing from the spirit ofthe invention.

Whatfis claimed is: l f f 1. The process of preparing Vand separating anaqueous solution of a cobaltous salt of cobalt V'hydrocarb'onyl suitablefor catalyzing a reaction of an oleiinic carboncompound with carbonmonoxide and vhydrogen which comprises initiallytreating an aqueoussolution of an or-V ganic cobaltsalt which supplies Co++ ions with aVgaseous mixture of hydrogen and carbon monoxide inthe presf ence or aninert oxygenated organic solvent therefor, reactants at atemperaturebetween about and 180 Yin the resulting liquid reaction mixtureV in suchquantity. that it provides cobaltous ions at least in suiicient amountsto combine with all Co(CO4)fV ions present in the aqueous phase to formthe cobalt salt of cobalt hydrocarbonyl, discharging unconverted gaseskfrom Vthe resulting reaction mixture, separating the residual liquidreaction mixture into an organic liquid phase'an'd'an aqueous liquidphase containing Vthe cobaltous 'salt of cobalt hydrocarbonyl. Y Y

2. A process as in claim 1,'in which the inert oxygenated organicsolvent isV selected from Vthe class consisting of aldehydes andalcohols'having at least 4 carbon atoms per molecule. Y

3. The process as in claim 1, inrwhich the elevated pressure maintainedon said reaction mixture is 1000 Vto 4000 p. s. i. g.

4. The processY as in claim 1, in which the organic liquid phaseseparated fromV the residual reaction mhi- Y ture is reused in treatingmoreV of said aqueousV solution of the organic cobalt salt.

5. A process of preparing Yand separating an aqueous Vsolution ofcobaltous rsalt of cobalt hydrocarbonyl suitablefor catalyzing thereaction of Van olen'icrc'arbon compound, carbon monoxide and hydrogen,whichV comprises initially treating an aqueous solution of cobaltousacetate which supplies Co++ ionswith a gaseousmixture the obtainingVsimilar conditions as cobalt suchV The Co(CO)4V Vis theV difference Y C.under Y' an elevated pressure, maintaining the organicrcobalt saltolenie carbon compound, at a temperature between about 90 and 180 C. anda pressure of 1000 to 4000 p. s. i. g., maintaining the cobaltousacetate in the reaction mixture in amounts such that it provides theCo++ ions at least in suicient amounts to combine with all C0(CO4)" ionspresent in the aqueous phase, discharging unconverted gases from theresulting reaction IniX- ture, separating the resulting liquid reactionmixture into an aldehyde phase and an aqueous phase containing thecobaltous salt of cobalt hydrocarbonyl, and withdrawing the aqueousphase containing the cobalt salt of cobalt hydrocarbonyl.

References Cited in the le of this patent UNITED STATES PATENTS OTHERREFERENCES Blanchard: Chemical Reviews, vol. 21, No. 1, pages 1 1s-19(August 1937).

1. THE PROCESS OF PREPARING AND SEPARATING AN AQUEOUS SOLUTION OF ACOBALTOUS SALT OF COBALT HYDROCARBONYL SUITABLE FOR CATALYZING AREACTION OF AN OLEFINIC CARBON COMPOUND WITH CARBON MONOXIDE ANDHYDROGEN WHICH COMPRISES INITIALLY TREATING AN AQUEOUS SOLUTION OF ANORGANIC COBALT SALT WHICH SUPPLIES CO++ IOS WITH A GASEOUS MIXTURE OFHYDROGEN AND CARBON MONOXIDE IN THE PRESENCE OF AN INERT OXYGENATEDORGANIC SOLVENT THEREFOR, PRIOR TO CONTACTING SAID SOLUTION WITH ORGANICREACTANTS AT A TEMPERATURE BETWEEN ABOUT 90* AND 180* C. UNDER ANELEVATED PRESSURE, MAINTAINING THE ORGANIC COBALT SALT IN THE RESULTINGLIQUID REACTION MIXTURE IN SUCH QUANTITY THAT IT PROVIDES COBALTOUS IONSAT LEAST IN SUFFICIENT AMOUNTS TO COMBINE WITH ALL CO(CO4)-IONS PRESENTIN THE AQUEOUS PHASE TO FORM THE COBALT SALT OF COBALT HYDROCARBONYL,DISCHARGING UNCONVERTED GASES FROM THE RESULTING REACTION MIXTURE,SEPARATING THE RESIDUAL LIQUID REACTION MIXTURE INTO AN ORGANIC LIQUIDPHASE AND AN AQUEOUS LIQUID PHASE CONTAINING THE COBALTOUS SALT OFCOBALT HYDROCARBONYL.